1. Field of the Invention
This invention relates to cooling systems and methods for lasers. More specifically, the invention is a thin-film evaporative cooling system and method for use with side-pumped lasers.
2. Description of the Related Art
The essential elements of a side-pumped laser are the laser's crystal rod and one or more laser diodes that are spaced apart from the radial surface of the crystal rod. The laser diode(s) “pump” light energy radially into the crystal rod. Due to the low optical efficiencies of luminescent crystals, most of the incident energy is converted into heat. The quality of the luminescent crystal output is typically characterized by the pulse energy, and the central tendency around a single output wavelength. The pulse energy is increased with lower average crystal temperatures while the output wavelength is affected by temperature as well. Consequently, large temperature gradients across the crystal (i.e., normal to the rod's cross-section) produce a wide variance in the output wavelength. Consequently, a side-pumped laser crystal thermal management system has three goals:
1. Prevent thermally-induced damage due to thermally-induced stresses.
2. Maintain the crystal rod at as low a temperature as possible.
3. Minimize temperature variation across the crystal rod.
Currently, conductive cooling is used for thermal management in many side-pumped lasers. Typically, a thermally-conductive support structure is coupled to the crystal rod. While totally passive, conductively-cooled configurations generate insufficient cooling, produce non-uniform temperature distributions across the crystal rod's cross-section, and are sensitive to minor variations in contact pressure at the conductive interface.